This invention relates to a machine tool equipped with an automatic tool changer.
A conventional machine tool with an automatic tool changer has an arm for interchanging tools. The arm is attached to a column or a base of the machine tool.
When a workpiece is machined, a spindle is rotated and a spindle head is moved. Until the machining is completed, the arm of the automatic tool changer is retained at a waiting position away from the spindle. Once machining with the tool set into the spindle is completed, the arm is moved toward the spindle so as to grip and draw out the tool.
On the other hand, after the arm returns the used tool to a tool magazine, the arm is retracted and maintained away from the tool magazine. The tool magazine is indexed so that a new tool is sent to the tool changing position. Next, the arm is again moved toward the tool magazine so as to grip the new tool.
Further, in the conventional machine, the end face of the spindle is located at the same level or plane as the end face of the tool magazine. When exchanging tools, the arm is moved in the following manner. First, the arm gripping the used tool set into the spindle is moved in a parallel motion so as to withdraw the used tool. Next, the arm is swiveled to a position beneath the tool magazine. Finally, the arm is moved toward the tool magazine in a parallel motion so as to return the tool into the tool magazine.
Because the arm uselessly moves in such a manner, the mechanism of the arm cannot be simple and the tool changing operation cannot be finished in a short time.